U.S. Pat. No. 3,897,021 discloses a dual package winder wherein two strands of glass filaments drawn from a bushing are wound into separate cylindrical packages axially aligned on a single winding collet. A package builder of the winder includes two axially aligned cylindrical or barrel cams fixedly mounted on a rotatable shaft and each driving a strand guide member back and forth axially along a respective one of the packages being wound. Each strand guide member is mounted on one end of a flat spring member attached at the other end to a slide block mounted in a longitudinal slot in a tubular housing for the barrel cams and pivotally connected to a cam follower disposed in a groove of the respective barrel cam. The cam housing has two switches mounted thereon respectively midway of the barrel cams, and each spring member carries a switch actuating means on the side opposite the strand guide member. The package builder is mounted on a motor driven carriage operable to move the builder toward or away from the winding collet.
The glass filaments vary in diameter if the temperature of the bushing bottom becomes non-uniform. Glass from relatively cooler orifices is attenuated less, resulting in larger filaments. One of the packages being wound may thus become larger than the other when bushing temperature imbalances occur. The larger package will be the first to bend the flat spring member associated with its respective strand guide member sufficiently for the switch actuating means thereon to close the respective switch on the cam housing as it passes by and thereby energize the carriage motor for a controlled time interval. The carriage is then moved in a direction to move the builder a certain distance away from the packages being wound. If there is much difference in the sizes of the packages, the strand guide member for the smaller package will be moved too far away and cause the smaller package to be wound too loosely into a package with flared ends. Such flared-end packages are not within customer acceptance standards and must be scrapped.